Transport in Living Things

The Human Circulatory System

Transport System : an orderly manner of moving things

Transport : to move things from one place to another

Why muliticellular organisms need one ??

- Cells need a supply of oxygen & nutrients ,
and at the same time need to remove carbon dioxide and other waste products.
- In most large organisms , most cells are far away from the outside .
Substances cannot enter or leave these cells directly unlike cells like Amoeba.
- Thus a transport system is needed to move substances in and out of the cells in the body.

The Human Circulatory System is made up of :
- Heart (A Pump which pushes blood around the body)
- Blood Vessels (A network of tubes to carry blood around the body )
- Blood (A liquid that transport materials)

Heart has 4 chambers. :
- 2 smaller upper chambers called the atrium ,
- 2 larger lower chambers called the ventricles.

Blood Vessels
- Arteries
-Veins
-Capillaries


Arteries V.S. Veins

Arteries
- Arteries have thick muscular walls.
-Carries blood away from the heart to all parts of the body.
-Blood rich in oxygen.
Reasons :
-Have thick walls to withstand the pressure of the blood flowing through them.

-Veins
-Veins have thin muscular walls.
-Carries blood to the heart from all parts of the body.
Reasons:
-The Pressure is lower in the veins , they have thinner walls than arteries.

Capillaries
-Very thin blood vessels found between all cells in body.
-help in release of excess heat from the body
Reasons:
-Allows substances to pass through them into the cells and from the cells into the blood.

Blood
Functions
- To carry blood to and from body cells
-It is a suspension of red blood cells, white blood cells and platelets ,in plasma

RBC
-Circular & Bioconcave shape
-No nucleus
-Contains haemoglobin
-Transport oxygen

WBC
-Irregular Shape & Larger than RBC
-Phagocytes : Destroy bacteria by engulfing them.
-Lymphocytes : Produce antibodies that kill bacteria.

Plasma
-Pale yellow liquid
-Made up of water and dissolved substances (digested food, waste products).

Platelets
-Tiny pieces of cells
-Role in blood clotting

Blood Circulation
Double Circulation
1) From the heart to lungs and back to heart again
2) From the heart to rest of the body and back again

Oygen - Carbon Dioxide -exchange
Blood
-Supplies oxgen to cells
-Collects Carbon Dioxide from cells

Absorption of digested food
-Digested food molecules absorbed into blood from small intestine transported to all parts of the body

thats all for now !! xD
A lot leh.... hais
hope they come out for exam lah
;D